lld-link: Set PDB GUID to hash of PDB contents instead of to a random byte sequence.
Previously, lld-link would use a random byte sequence as the PDB GUID. Instead,
use a hash of the PDB file contents.
To not disturb llvm-pdbutil pdb2yaml, the hash generation is an opt-in feature
on InfoStreamBuilder and ldb/COFF/PDB.cpp always sets it.
Since writing the PDB computes this ID which also goes in the exe, the PDB
writing code now must be called before writeBuildId(). writeBuildId() for that
reason is no longer included in the "Code Layout" timer.
Since the PDB GUID is now a function of the PDB contents, the PDB Age is always
set to 1. There was a long comment above loadExistingBuildId (now gone) about
how not changing the GUID and only incrementing the age was important, but
according to the discussion in PR35914 that comment was incorrect.
Differential Revision: https://reviews.llvm.org/D51956
llvm-svn: 342334
diff --git a/lld/COFF/PDB.cpp b/lld/COFF/PDB.cpp
index 0c77d39..b22ed14 100644
--- a/lld/COFF/PDB.cpp
+++ b/lld/COFF/PDB.cpp
@@ -98,7 +98,7 @@
}
/// Emit the basic PDB structure: initial streams, headers, etc.
- void initialize(const llvm::codeview::DebugInfo &BuildId);
+ void initialize(llvm::codeview::DebugInfo *BuildId);
/// Add natvis files specified on the command line.
void addNatvisFiles();
@@ -130,8 +130,8 @@
void addSections(ArrayRef<OutputSection *> OutputSections,
ArrayRef<uint8_t> SectionTable);
- /// Write the PDB to disk.
- void commit();
+ /// Write the PDB to disk and store the Guid generated for it in *Guid.
+ void commit(codeview::GUID *Guid);
private:
BumpPtrAllocator Alloc;
@@ -380,8 +380,8 @@
return std::move(NS);
}
-Expected<const CVIndexMap&> PDBLinker::maybeMergeTypeServerPDB(ObjFile *File,
- TypeServer2Record &TS) {
+Expected<const CVIndexMap &>
+PDBLinker::maybeMergeTypeServerPDB(ObjFile *File, TypeServer2Record &TS) {
const GUID &TSId = TS.getGuid();
StringRef TSPath = TS.getName();
@@ -1230,7 +1230,7 @@
void coff::createPDB(SymbolTable *Symtab,
ArrayRef<OutputSection *> OutputSections,
ArrayRef<uint8_t> SectionTable,
- const llvm::codeview::DebugInfo &BuildId) {
+ llvm::codeview::DebugInfo *BuildId) {
ScopedTimer T1(TotalPdbLinkTimer);
PDBLinker PDB(Symtab);
@@ -1240,12 +1240,19 @@
PDB.addNatvisFiles();
ScopedTimer T2(DiskCommitTimer);
- PDB.commit();
+ codeview::GUID Guid;
+ PDB.commit(&Guid);
+ memcpy(&BuildId->PDB70.Signature, &Guid, 16);
}
-void PDBLinker::initialize(const llvm::codeview::DebugInfo &BuildId) {
+void PDBLinker::initialize(llvm::codeview::DebugInfo *BuildId) {
ExitOnErr(Builder.initialize(4096)); // 4096 is blocksize
+ BuildId->Signature.CVSignature = OMF::Signature::PDB70;
+ // Signature is set to a hash of the PDB contents when the PDB is done.
+ memset(BuildId->PDB70.Signature, 0, 16);
+ BuildId->PDB70.Age = 1;
+
// Create streams in MSF for predefined streams, namely
// PDB, TPI, DBI and IPI.
for (int I = 0; I < (int)pdb::kSpecialStreamCount; ++I)
@@ -1253,15 +1260,12 @@
// Add an Info stream.
auto &InfoBuilder = Builder.getInfoBuilder();
- GUID uuid;
- memcpy(&uuid, &BuildId.PDB70.Signature, sizeof(uuid));
- InfoBuilder.setAge(BuildId.PDB70.Age);
- InfoBuilder.setGuid(uuid);
InfoBuilder.setVersion(pdb::PdbRaw_ImplVer::PdbImplVC70);
+ InfoBuilder.setHashPDBContentsToGUID(true);
// Add an empty DBI stream.
pdb::DbiStreamBuilder &DbiBuilder = Builder.getDbiBuilder();
- DbiBuilder.setAge(BuildId.PDB70.Age);
+ DbiBuilder.setAge(BuildId->PDB70.Age);
DbiBuilder.setVersionHeader(pdb::PdbDbiV70);
DbiBuilder.setMachineType(Config->Machine);
// Technically we are not link.exe 14.11, but there are known cases where
@@ -1305,9 +1309,9 @@
DbiBuilder.addDbgStream(pdb::DbgHeaderType::SectionHdr, SectionTable));
}
-void PDBLinker::commit() {
+void PDBLinker::commit(codeview::GUID *Guid) {
// Write to a file.
- ExitOnErr(Builder.commit(Config->PDBPath));
+ ExitOnErr(Builder.commit(Config->PDBPath, Guid));
}
static Expected<StringRef>